[PATCH 2/2] Fix for full and semi-transparency under negative image.

[Mattias Andrée]

---
 hw/xfree86/modes/xf86Cursors.c | 49 +++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 12 deletions(-)

diff --git a/hw/xfree86/modes/xf86Cursors.c b/hw/xfree86/modes/xf86Cursors.c
index 3cb499f..5afd740 100644
--- a/hw/xfree86/modes/xf86Cursors.c
+++ b/hw/xfree86/modes/xf86Cursors.c
@@ -209,6 +209,41 @@ set_bit(CARD8 *image, xf86CursorInfoPtr cursor_info, int x, int y, Bool mask)
 }
 
 /*
+ * Remap a cursor pixel according to the gamma ramps
+ */
+static CARD32
+cursor_gamma_correct(xf86CrtcPtr crtc, CARD32 bits)
+{
+    float  alpha;
+    CARD32 old_red,   new_red;
+    CARD32 old_green, new_green;
+    CARD32 old_blue,  new_blue;
+
+    if (!(crtc->gamma_red && crtc->gamma_size == 256))
+        return bits;
+
+    alpha = (float)((bits >> 24) & 255) / 255.f;
+
+    old_red   = (bits >> 16) & 255;
+    old_green = (bits >>  8) & 255;
+    old_blue  = (bits >>  0) & 255;
+
+    new_red   = (crtc->gamma_red  [old_red  ]) >> 8;
+    new_green = (crtc->gamma_green[old_green]) >> 8;
+    new_blue  = (crtc->gamma_blue [old_blue ]) >> 8;
+
+    new_red   = new_red   * alpha + old_red   * (1 - alpha);
+    new_green = new_green * alpha + old_green * (1 - alpha);
+    new_blue  = new_blue  * alpha + old_blue  * (1 - alpha);
+
+    new_red   = new_red   < 0 ? 0 : new_red   > 255 ? 255 : new_red;
+    new_green = new_green < 0 ? 0 : new_green > 255 ? 255 : new_green;
+    new_blue  = new_blue  < 0 ? 0 : new_blue  > 255 ? 255 : new_blue;
+
+    return (bits & 0xFF000000) | (new_red << 16) | (new_green << 8) | (new_blue << 0);
+}
+
+/*
  * Load a two color cursor into a driver that supports only ARGB cursors
  */
 static void
@@ -242,12 +277,7 @@ xf86_crtc_convert_cursor_to_argb(xf86CrtcPtr crtc, unsigned char *src)
             }
             else
                 bits = 0;
-            if (crtc->gamma_red && crtc->gamma_size == 256) {
-                bits = (bits & 0xFF000000) |
-                       ((crtc->gamma_red[(bits >> 16) & 255] >> 8) << 16) |
-                       (crtc->gamma_green[(bits >> 8) & 255] & 0xFF00) |
-                       (crtc->gamma_blue[bits & 255] >> 8);
-            }
+            bits = cursor_gamma_correct(crtc, bits);
             cursor_image[y * cursor_info->MaxWidth + x] = bits;
         }
     crtc->funcs->load_cursor_argb(crtc, cursor_image);
@@ -547,12 +577,7 @@ xf86_crtc_load_cursor_argb(xf86CrtcPtr crtc, CursorPtr cursor)
                 bits = cursor_source[yin * source_width + xin];
             else
                 bits = 0;
-            if (crtc->gamma_red && crtc->gamma_size == 256) {
-                bits = (bits & 0xFF000000) |
-                       ((crtc->gamma_red[(bits >> 16) & 255] >> 8) << 16) |
-                       (crtc->gamma_green[(bits >> 8) & 255] & 0xFF00) |
-                       (crtc->gamma_blue[bits & 255] >> 8);
-            }
+            bits = cursor_gamma_correct(crtc, bits);
             cursor_image[y * image_width + x] = bits;
         }
 
-- 
1.9.2